Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #12496

Re: Why do class methods always need 'self' as the first parameter?

Show key headers only | View raw

On 8/31/2011 10:35 AM, T. Goodchild wrote:

> But one of the things that bugs me is the requirement that all class
> methods have 'self' as their first parameter.  On a gut level, to me
> this seems to be at odds with Python’s dedication to simplicity.

Actually, it is a consequence of Python's dedication to simplicity. A 
method is simply a function that is an attribute of a class. (This is 
even clearer in Py 3.) Hence, there is no special syntax for methods.

Consider

def double(obj): return 2*obj.value

class C:
     def __init__(self, val):
         self.value = val

c = C(3)
C.double = double
c.doub = double
# not c.double as that would mask access to C.double in c.double() below
print(double(c), C.double(c), c.double(), c.doub(c))
# 6 6 6 6

-- 
Terry Jan Reedy

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Why do class methods always need 'self' as the first parameter? "T. Goodchild" <tgoodchild@gmail.com> - 2011-08-31 07:35 -0700
  Re: Why do class methods always need 'self' as the first parameter? John Gordon <gordon@panix.com> - 2011-08-31 14:54 +0000
    Re: Why do class methods always need 'self' as the first parameter? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-01 02:06 +1000
      Re: Why do class methods always need 'self' as the first parameter? Grant Edwards <invalid@invalid.invalid> - 2011-08-31 16:20 +0000
  Re: Why do class methods always need 'self' as the first parameter? Emile van Sebille <emile@fenx.com> - 2011-08-31 08:01 -0700
  Re: Why do class methods always need 'self' as the first parameter? Neil Cerutti <neilc@norwich.edu> - 2011-08-31 15:05 +0000
  Re: Why do class methods always need 'self' as the first parameter? Javier Collado <javier.collado@gmail.com> - 2011-08-31 17:10 +0200
  Re: Why do class methods always need 'self' as the first parameter? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-01 01:41 +1000
    Re: Why do class methods always need 'self' as the first parameter? Chris Torek <nospam@torek.net> - 2011-08-31 20:15 +0000
      Re: Why do class methods always need 'self' as the first parameter? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-01 10:48 +1000
        Re: Why do class methods always need 'self' as the first parameter? Chris Angelico <rosuav@gmail.com> - 2011-09-01 11:47 +1000
        Re: Why do class methods always need 'self' as the first parameter? Eric Snow <ericsnowcurrently@gmail.com> - 2011-08-31 20:07 -0600
        Re: Why do class methods always need 'self' as the first parameter? Chris Torek <nospam@torek.net> - 2011-09-01 02:20 +0000
      Re: Why do class methods always need 'self' as the first parameter? Piet van Oostrum <piet@vanoostrum.org> - 2011-09-05 16:15 +0200
        Re: Why do class methods always need 'self' as the first parameter? Chris Torek <nospam@torek.net> - 2011-09-06 01:10 +0000
          Re: Why do class methods always need 'self' as the first parameter? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-06 14:31 +1000
  Re: Why do class methods always need 'self' as the first parameter? Terry Reedy <tjreedy@udel.edu> - 2011-08-31 12:30 -0400
  RE: Why do class methods always need 'self' as the first parameter? "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2011-08-31 13:12 -0400
    Re: Why do class methods always need 'self' as the first parameter? Piet van Oostrum <piet@vanoostrum.org> - 2011-09-08 01:01 +0200
  Re: Why do class methods always need 'self' as the first parameter? Chris Rebert <clp2@rebertia.com> - 2011-08-31 11:31 -0700
  Re: Why do class methods always need 'self' as the first parameter? Ian Kelly <ian.g.kelly@gmail.com> - 2011-08-31 15:52 -0600
  Re: Why do class methods always need 'self' as the first parameter? Terry Reedy <tjreedy@udel.edu> - 2011-08-31 18:40 -0400
  Re: Why do class methods always need 'self' as the first parameter? UncleLaz <andrei.lisnic@gmail.com> - 2011-09-01 03:40 -0700
    Re: Why do class methods always need 'self' as the first parameter? Michiel Overtoom <motoom@xs4all.nl> - 2011-09-01 13:23 +0200
  Re: Why do class methods always need 'self' as the first parameter? John Roth <johnroth1@gmail.com> - 2011-09-01 05:45 -0700
    Re: Why do class methods always need 'self' as the first parameter? Ian Kelly <ian.g.kelly@gmail.com> - 2011-09-01 08:26 -0600
      Re: Why do class methods always need 'self' as the first parameter? John Roth <johnroth1@gmail.com> - 2011-09-02 10:51 -0700
        Re: Why do class methods always need 'self' as the first parameter? Ian Kelly <ian.g.kelly@gmail.com> - 2011-09-02 14:30 -0600
          Re: Why do class methods always need 'self' as the first parameter? John Roth <johnroth1@gmail.com> - 2011-09-02 15:30 -0700
  Re: Why do class methods always need 'self' as the first parameter? rantingrick <rantingrick@gmail.com> - 2011-09-05 20:58 -0700

csiph-web